Onion dome

An onion dome, also known as onion cupola, is a dome whose shape resembles an onion. Such domes are often larger in diameter than the tholobate (drum) upon which they sit, and their height usually exceeds their width. They taper smoothly upwards to a point.

This feature is typically associated with churches belonging to the Russian Orthodox Church, although they also persist in other Eastern European countries, and occasionally in Western Europe: Bavaria (Germany), Austria, and northeastern Italy. Buildings with onion domes are also found in the Oriental regions of Central and South Asia, and the Middle East.

Other types of Eastern Orthodox cupolas include helmet domes (for example, those of the Dormition Cathedral in Vladimir), Ukrainian pear domes (St Sophia Cathedral in Kyiv), and Baroque bud domes (St Andrew's Church in Kyiv) or an onion-helmet mixture like the St Sophia Cathedral in Novgorod.

According to historian Wolfgang Born, the onion dome has its origin in Syria, where some Umayyad Caliphate-era mosaics depict early stages of the development of bulbous domes. An early prototype of onion dome also appeared in Chechel Dockhter, a mid-11th century Seljuk architecture in Damghan region of Iran.

It is not completely clear when and why the onion dome gained popularity in Russian architecture, but buildings featuring them appeared as early as the 13th century, reaching a peak by the 17th and 18th centuries, up until the Petrine period. Some suggest they had a decorative advantage over typical Byzantine and helmet dome, while also not gathering as much snow during severe winters. The largest onion domes of that time were erected in areas around Yaroslavl. A number of these had more complicated bud-shaped domes, whose form derived from Baroque models of the late seventeenth century. Pear-shaped domes are usually associated with Ukrainian Baroque, while cone-shaped domes are typical for Orthodox churches of Transcaucasia.^{[citation needed]}

Later, the Moors also brought the design to Spain, and Islamic influence in the 17th century may be responsible for its introduction in Vienna, where it can be seen on many Baroque structures. Throughout Austria and Bavaria, onion domes top innumerable small churches.

Some scholars suggest that onion domes first appeared in Russia during the reign of Ivan the Terrible (r. 1533–1584). The domes of Saint Basil's Cathedral have not been altered since the reign of Ivan's son Fyodor I (r. 1584–1598), indicating the presence of onion domes in sixteenth-century Russia. Thus, Russians may have adopted onion domes from Muslim countries, possibly from the Khanate of Kazan, whose conquest in 1552 Ivan the Terrible commemorated by erecting St. Basil's Cathedral. Some scholars believe that onion domes first appeared in Russian wooden architecture above tent-like churches. According to this theory, they were strictly utilitarian.

In 1946 Boris Rybakov analysed russian chronicles and concluded, that most of them, from the 13th century onward, feature onion instead of helmet shaped dome, suggesting that this style could not be imported from the Orient, where they did not replace spherical domes until the 15th century Historians like Nikolay Voronin seconded his point of view.